How Are Japanese Trains Powered?


Input Power Supply

Electricity to power the trains is produced at the power company’s power plant at 22,000V AC and reaches the railroad company’s substation through a special high-voltage transmission line. Here, it is converted to 1,500V DC to supply power to the overhead lines. The train receives the 1,500 VDC from the power collector, and various control devices generate the necessary voltage to rotate the main electric motor (motor) to run.

When the train reaches a predetermined speed, it stops consuming power and continues running by coasting only. One-mass control handle, Series E231 JR East, Toei Subway 6300, overhead line input voltmeter Regenerative braking, which “generates braking power” and “returns electricity to the overhead lines” when decelerating from coasting, has become the mainstream. This “return of electricity to the overhead wires” means that when regenerative braking is used, it assists the power consumption of other trains running on the same line.

Since large amounts of electricity cannot be stored, this energy-saving system can be said to reduce power consumption at the same substation. The main motors of the power source include DC double-winding commutator motors, cage-type 3-phase AC induction motors, and permanent magnet synchronous motors, each of which has different characteristics.
The right side of the voltmeter in the driver’s cab in Photo 2 shows the overhead line voltage of 1,500 VDC.

The left side is the 100V+ power supply for in-train service.

Power operation is to start or accelerate the train by applying the necessary voltage to the main electric motor by turning on the notch of the mass controller (red circle in Photo 1 on the left).

Shinkansen, Joban Line (north of Toride Station) and Tsukuba Express (north of Moriya Station) use AC power. Resistance control The main electric motor, which powers the train, changes its speed in proportion to the voltage flowing through the field magnet (stator) and armature (rotor). If the power supply is direct current, the power is controlled by inserting a resistor between the positive value on the overhead line side and the negative value on the track side. The photo on the right shows the resistor device of a Seibu 2000 Series 2011F train.

The resistor control device of this train is attached to the field chopper control device, and it performs startup and power running by resistor control and series-parallel combination control.

This is a resistor


This is a method to realize regenerative braking (see below) without changing the startup and power train by anti-control.


Resistor Device (Seibu 2000 Series) Resistor control refers to the use of a resistor device to control the main electric motor. The method of controlling the main electric motor and resistor together while switching between series and parallel is called series-parallel control.

This method was invented to mitigate the shock at startup, and is characterized by the sound of the relay that switches.

In actuality, the control method is to connect the motors in series at startup and connect them in parallel when the speed reaches about 30 km/h. Odakyu Type 5200 resistance-controlled car Keikyu Type 1000 resistance-controlled car


Various methods have been devised to smoothly increase the speed. There are about seven resistor control stages in one notch of the main controller, and the voltage is controlled by combining fixed resistors of various values. The structure is a combination of disk-shaped objects with protrusions on a single shaft, and the resistance value is changed by rotating the shaft.

Smoother movement was required in the method using the electric camshaft. While the train is accelerating, a resistance called “vernier resistance” is inserted between each control stage in the process of advancing the number of control stages of the electric camshaft type main controller. This method is called vernier resistance control, which has been modified so that the number of control stages is substantially increased and acceleration and deceleration become smooth. For vehicles equipped with a generator brake, it is also effective during deceleration.

Electric camshaft device


Vernier resistive control is used in the Odakyu Electric Railway Series 5000, Tobu Railway Series 200, 300, 1800, 6050, 8000, and other trains still in operation. However, the common problems are that it takes some time to switch over and consumes electricity unnecessarily, which is an issue for the next generation. Odakyu Electric Railway Type 5000 Tobu Railway Series 8000

Electric motor chopper control



Armature chopper control is the second method of controlling a DC motor after resistance control. It uses a chopper circuit connected to the motor’s armature circuit to control voltage. The basic idea of armature chopper control is to use a thyristor (a switch that can be turned on and off at high speed) to cut off only the necessary amount of electricity, and control with the average voltage. This method enables stepless control without steps, resulting in smooth startup and improved adhesion performance.

The electric chopper control method was first used in the Tokyo Subway Series 6000 in 1968.

Tokyo Subway Series 6000



This control method enabled stable regenerative braking in the mid- to low-speed range, reducing energy consumption and eliminating the need for brake resistors, thereby reducing the weight of the car body. It was the culmination of innovative technology at the time. Later, some electric railcars shifted to field chopper control due to the drawback of high production cost of armature chopper control. This system was developed to achieve regenerative braking at a lower cost while maintaining the startup and power operation by resistance control, and was first used in the Tokyu Electric Railway Series 8000 in 1969.
This train was equipped with a one-handle main controller (mass controller) for the first time.

Tokyu Corporation Series 8000 ■Field additive excitation control


Field additive excitation control utilizes a resistance-controlled DC direct-wound motor, but enables field adjustment using an auxiliary power supply (MG). The Series 205, newly introduced on the JR East Yamanote Line in 1985, is a resistance-controlled, series-parallel combination train that uses the CS57 type field-additive excitation control system. After leaving service in 2005, it was transferred to the Saikyo Line (photo left), Yokohama Line, Nambu Line, Keiyo Line, Musashino Line, etc., and is still in service. JR East 205 Seriesspace800-3


■Field Chopper Control

Field chopper control uses resistive control and series-parallel combination control for startup and power train, and chopper control only for the field circuit to control the speed by the magnitude of the back EMF. Since the main circuit is still resistance-controlled, the breakaway speed is as high as 20 to 40 km/h. Although not adopted by JR companies, this system was first adopted in Tokyu Corporation’s 8000 type, replacing the field regulator with a chopper system, and was also adopted in Keisei Electric Railway’s AE type (first generation). Field Chopper Controller ■

Thyristor Phase Control

Thyristor phase control is a method used in AC electrified sections. By taking out a part of the AC power waveform and performing phase control, this method drives the DC DC direct-wound motor by rectifying it after voltage control.

During regeneration, a thyristor is used as an inverter to convert the DC power generated by the motor into AC. This method is used in AC-only vehicles because the power source must be AC. The trains equipped with regenerative braking using thyristor phase control are the JR Kyushu Series 713 and 783, etc., which were introduced in 1984. VVVF inverter control (Variable Voltage Variable Frequency)space800-3


Until now, resistor control has wasted power due to heat.

VVVF inverter control does not require resistors as a heat source. An inverter is a power conversion device that outputs AC power from an overhead line voltage of 1,500 VDC, and the effective voltage and frequency of the output AC power can be controlled as desired. This control method is currently the mainstream control device. In variable voltage and frequency control, the DC power from the overhead line is chopped in pulses of width corresponding to the height of the sine wave, and the current is turned on and off repeatedly using a bridge circuit consisting of six switching elements such as thyristors and transistors, to produce pseudo-three-phase AC by varying the pulse width, thereby driving a three-phase AC induction motor. The bridge circuit consists of six switching elements such as thyristors and transistors. Odakyu Type 60000 (MSE) VVVF inverter device The use of insulated gate type bipolar IGBT transistors, which have a high switching speed, enables output closer to a sine wave and low noise of the inverter device and motor. VVVF is the English abbreviation for variable voltage variable frequency control.


The photo on the left shows a JR East 233 Series and Odakyu 4000 VVVF inverter-controlled car, which has an IPM 2-level VVVF inverter control system using IGBT elements manufactured by Mitsubishi Electric, and has regenerative braking and pure electric braking functions. The IC4M system consists of two IC4M units that control four cage-type three-phase AC induction motors (M) with a single inverter control (IC). East Japan Railway Series 233 Odakyu Type 4000



The photo above shows a Keio Electric Railway Series 8000 equipped with a VVVF inverter control system using Hitachi-made GTO thyristor elements. This is the first Keio Electric Railway train to adopt the VVVF inverter control system.

Master Control Unit (Master Control = Mass Control Unit)


The main controller that operates train operation is called a mass controller. Vertical mass controllers are broadly classified into vertical mass controllers (left photo) and one-handle mass controllers (right photo). The brake handle is located on the right side, and the handle is detachable to release in the emergency brake position. The one-handle mass control system operates “power, coasting, and braking” on a vertical axis with a single handle. Odakyu Type 8000 (unrenewed) Odakyu Type 8000 (renewed) The vertical mass control system of the previous generation enables fine running control by combining mass control and brake operation. This method relies heavily on the skill of the operator, which can be experienced when controlling the impact at startup. In this sense, there are many crew members who do not prefer the one-handle mass control system because it is difficult to control in detail.
*Coasting is the state in which the engine is turned off a notch.


The red circle in the photo above left shows the brake handle removed.  The Tokaido Shinkansen Series 0 put the vertical-axis mass control system into practical use. The operation of the mass controller was in the opposite direction of that used today: “Push to power, pull to coast. The brake handle was positioned on the left side and turned in the conventional lateral direction. This arrangement was continued for many years after the automatic pneumatic brake system was adopted and the automatic advance electric command brake system was introduced due to the custom of JNR crews who operated the brake lever directly from the cab. The JNR-type vertical-shaft mass-controlled trains were the reverse of the private railway type, although this arrangement was followed by Series 205, Series 211, and other trains on conventional lines.

The red circle in the photo on the left shows the brake handle removed. Tokaido Shinkansen Series 0 The one-handle mass control system, which is now the mainstream, was first adopted in earnest in 1969 with Tokyu Series 8000 trains. Since the appearance of this type, “push to brake, emergency, middle is coasting, pull to front to power” has been standardized on all railroads in Japan.


To install a one-handled mast controller, the power generation/regenerative brake operated by the mast controller and the air brake system operated by the brake valve must be electrically and mechanically synchronized, which is not a problem for newly built cars, but a requirement when upgrading existing cars.

The two-handled one-handled mast controller pictured at left uses both hands during operation. When both hands leave the handle, the dead man device is activated, and if it persists, the train stops for safety.

The two-handled type is used in newly built or upgraded trains of Tokyu Corporation, Keio Corporation, Tokyo Metro, Tokyo Metropolitan Transportation Bureau, Seibu Corporation, Tobu Corporation, Keihin Electric Express Railway, Keihin Electric Express Railway, Keisei Corporation, Tsukuba Express, and others. Keio Inokashira Line 1000 Series


The one-handled one-handle master controller shown in the left photo is used in newly built or renewed trains of JR East, Odakyu Electric Railway, Sagami Railway, and others. The one-handle handle on the left side of the driver’s cab provides space in the center of the cab for various switches, work charts, etc. The T-shaped handle on the right side is installed to keep the vehicle in a balanced posture while running. The EB device, equipped on the one-hand type, sounds an alarm buzzer and illuminates an alarm lamp to activate the emergency brake if no operation is performed for a certain period of time (about 1 minute).
The position of the mass control handle in the photo shows the emergency brake state with the lever pushed to the maximum notch. JR East E231 Series

Braking systems

Regenerative brakesspace800-3


An electric brake is an electric brake that operates an electric motor as a generator and brakes against rotation when electricity is generated. The type that returns electricity from the vehicle to the overhead wires is called a regenerative brake, while the type that converts it into heat energy in the vehicle by means of resistors, etc. and discards it is called a generator brake or an electric brake. The condition for regenerative braking is that the voltage on the vehicle side must be higher than that on the overhead line side. If the voltage is not higher, sufficient power regeneration cannot be achieved.

If power regeneration is not possible, a regenerative lapse phenomenon occurs, which reduces braking performance. To avoid this phenomenon, the train often switches from regenerative braking to power generation braking when the speed slows down. Brake Shoe The brake chopper device installed on Series E257 of East Japan Railway and Series 313 of Central Japan Railway, etc. can consume the extra power that cannot be regenerated to the overhead wires by the generator brake while using regenerative braking.

Electric Command Brakes For many years, automatic pneumatic brakes were used for rolling stock, but since the brakes of each car were controlled by pneumatic control of commands from the brake control valve in the driver’s cab, response to the demand for longer trains and higher speeds became a problem.

In the 1950s and later, electromagnetic automatic pneumatic brakes were developed to solve this problem by using solenoid valves with better response.

The electromagnetic direct-acting brake required a jumper wire to activate the solenoid valve, a direct-acting pipe to send commands, a main air reservoir pipe to send compressed air to each car, and an automatic air brake pipe to provide backup in case of emergency, and these three air pipes had to be drawn through. The electric-command brake is an evolution of this method, in which the direct-command pneumatic brake installed in each car is controlled solely by electric commands from the driver’s cab.

The electric-command brake system requires either a single main air reservoir pipe or a combination of a main air reservoir pipe and an automatic air brake pipe or an emergency pipe. This structure does not require air piping to be drawn into the driver’s cab, so it can be integrated with the main controller, making it possible to introduce one-handle mass control systems.

Recent models use an electronic control system that enables finer control through digitization (arithmetic processing). However, in addition to the electric command brake, an automatic pneumatic brake with “emergency pipe + emergency valve” is provided as an emergency brake bypass. The Odakyu Electric Railway Type 3000 and Type 8000 (renewal cars) are equipped with a brake reading device that can be used when coupled with a train that uses electric brakes and direct electromagnetic brakes with a different mechanism.

Delay-loading control Delay-loading control directs the brake force to each car according to the differences in weight and brake performance of each car.

The delay-loading control is a method of instructing each car to apply the brake force according to the differences in weight and brake performance of each car. To achieve uniform braking action in each car, electric command or electro-pneumatic coordinated control is used. Even in general electro-pneumatic coordinated control, it is necessary to make the “combined force of electric and air brake forces” uniform in each train formation. A train formation consists of electric cars equipped with main electric motors and non-electric cars, and only electric cars can use electric brakes. The delay-loading control was developed to give priority to the electric brakes of the electric cars and to equalize the braking force.